Fiber mode-locked lasers are widely used in time-resolved imaging, but at repetition rates in the hundred kHz range, amplified spontaneous emission (ASE) poses a major concern. To address this problem, this paper presents a straightforward approach to achieving a low repetition rate and low noise fiber femtosecond laser. A cascade acoustic optical pulse picker is employed to effectively suppress ASE noise, resulting in an achieved maximum signal-to-noise ratio of 45 at a repetition rate of 50 kHz. The amplification property of the Er-doped fiber amplification is precisely presented by measuring pulse energy at different repetition rates. The potential for time-resolved imaging is demonstrated with high confidence through single pulse interferometry modulated by electro-optic modulation, which exhibits low ASE levels, and ultrafast imaging using the multiple exposure imaging system, which reveals sufficient light intensity levels.
{"title":"Low-noise fiber femtosecond laser with cascade acoustic-optical pulse picker for time-resolved imaging","authors":"Yang Lu, Zixuan Han, Yilin Tian, Yongan Wen, Feifei Wang, Huakun Jia, Rongke Gao, Liandong Yu","doi":"10.1016/j.optcom.2025.131583","DOIUrl":"10.1016/j.optcom.2025.131583","url":null,"abstract":"<div><div>Fiber mode-locked lasers are widely used in time-resolved imaging, but at repetition rates in the hundred kHz range, amplified spontaneous emission (ASE) poses a major concern. To address this problem, this paper presents a straightforward approach to achieving a low repetition rate and low noise fiber femtosecond laser. A cascade acoustic optical pulse picker is employed to effectively suppress ASE noise, resulting in an achieved maximum signal-to-noise ratio of 45 at a repetition rate of 50 kHz. The amplification property of the Er-doped fiber amplification is precisely presented by measuring pulse energy at different repetition rates. The potential for time-resolved imaging is demonstrated with high confidence through single pulse interferometry modulated by electro-optic modulation, which exhibits low ASE levels, and ultrafast imaging using the multiple exposure imaging system, which reveals sufficient light intensity levels.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131583"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143222213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.optcom.2025.131554
Ruitao Zhang , Ye Tian , Junpeng Liao , Haoda Xu , Guangbiao Zhong , Yegang Lu , Yan Li , Shile Wei , Huihong Zhang
Arbitrary ratio power splitters (ARPSs) operating across multiple modes can significantly streamline on-chip mode-division-multiplexing (MDM) systems. However, most ARPSs are designed for single-mode operation. This study introduces a shape optimization method to develop a dual-mode power splitter, enabling simultaneous arbitrary power distribution for both TE0 and TE1 modes within a compact size of 16 m 3 m. Various splitters with different ratios were created to validate this approach. Across a bandwidth from 1520 nm to 1580 nm, these splitters matched their target ratios with imbalance deviations within ±1 dB and excess loss (EL) below 1.75 dB. Experimental verification of a dual-mode splitter with a 1:2 ratio showed an imbalance deviation within ±0.75 dB and an EL below 1.44 dB over the bandwidth.
{"title":"Arbitrary ratio power splitter based on shape optimization for dual-mode operation","authors":"Ruitao Zhang , Ye Tian , Junpeng Liao , Haoda Xu , Guangbiao Zhong , Yegang Lu , Yan Li , Shile Wei , Huihong Zhang","doi":"10.1016/j.optcom.2025.131554","DOIUrl":"10.1016/j.optcom.2025.131554","url":null,"abstract":"<div><div>Arbitrary ratio power splitters (ARPSs) operating across multiple modes can significantly streamline on-chip mode-division-multiplexing (MDM) systems. However, most ARPSs are designed for single-mode operation. This study introduces a shape optimization method to develop a dual-mode power splitter, enabling simultaneous arbitrary power distribution for both TE<sub>0</sub> and TE<sub>1</sub> modes within a compact size of 16 <span><math><mi>μ</mi></math></span>m <span><math><mo>×</mo></math></span> 3 <span><math><mi>μ</mi></math></span>m. Various splitters with different ratios were created to validate this approach. Across a bandwidth from 1520 nm to 1580 nm, these splitters matched their target ratios with imbalance deviations within ±1 dB and excess loss (EL) below 1.75 dB. Experimental verification of a dual-mode splitter with a 1:2 ratio showed an imbalance deviation within ±0.75 dB and an EL below 1.44 dB over the bandwidth.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131554"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143222214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.optcom.2025.131577
Yunshan Sun , Wenxiang Wang , Ting Liu , Jingyu Zhang , Teng Fei , Yuhan Guo
Coati Optimization Algorithm has drawbacks, including reduced optimization accuracy in the search space and a tendency to get trapped in local optima. To address these shortcomings, this paper proposes an Enhanced Coati Optimization Algorithm (EnCOA). Firstly, to address the shortcomings of the traditional COA, which tends to local optimization guided by iguana, a convex lens imaging strategy and mutation perturbation are proposed to enhance population diversity and improve the algorithm’s global exploration capability. Secondly, the concepts of bidirectional grouping in the teaching phase of the Teaching-Learning-Based Optimization and the cosine learning factor are introduced to improve convergence speed and accuracy. Finally, the water wave dynamic adaptive factor is utilized to enhance the stability of the COA. The performance of EnCOA is assessed using various benchmark functions, including those from CEC2017, to highlight its effectiveness in optimization tasks. Furthermore, Visible Light Communication (VLC) provides high transmission speeds, robust interference immunity, and low energy consumption, positioning it as an effective solution for high-speed data transmission needs. To enhance system performance, Non-Orthogonal Multiple Access (NOMA) is integrated into the VLC framework. This study focuses on power allocation within the NOMA-VLC framework, with the goal of maximizing user rates while ensuring fairness. Simulation results show that EnCOA outperforms other algorithms in power allocation within the NOMA-VLC framework, especially under varying user numbers, residual interference, LED application scenarios, and shifts in photodetector alignment. EnCOA consistently demonstrates efficient power distribution and superior performance under complex communication conditions. Therefore, EnCOA is of significant importance in solving global optimization problems and power allocation challenges in NOMA-VLC systems.
{"title":"Enhanced coati optimization algorithm and its application in power allocation for NOMA-VLC systems","authors":"Yunshan Sun , Wenxiang Wang , Ting Liu , Jingyu Zhang , Teng Fei , Yuhan Guo","doi":"10.1016/j.optcom.2025.131577","DOIUrl":"10.1016/j.optcom.2025.131577","url":null,"abstract":"<div><div>Coati Optimization Algorithm has drawbacks, including reduced optimization accuracy in the search space and a tendency to get trapped in local optima. To address these shortcomings, this paper proposes an Enhanced Coati Optimization Algorithm (EnCOA). Firstly, to address the shortcomings of the traditional COA, which tends to local optimization guided by iguana, a convex lens imaging strategy and mutation perturbation are proposed to enhance population diversity and improve the algorithm’s global exploration capability. Secondly, the concepts of bidirectional grouping in the teaching phase of the Teaching-Learning-Based Optimization and the cosine learning factor are introduced to improve convergence speed and accuracy. Finally, the water wave dynamic adaptive factor is utilized to enhance the stability of the COA. The performance of EnCOA is assessed using various benchmark functions, including those from CEC2017, to highlight its effectiveness in optimization tasks. Furthermore, Visible Light Communication (VLC) provides high transmission speeds, robust interference immunity, and low energy consumption, positioning it as an effective solution for high-speed data transmission needs. To enhance system performance, Non-Orthogonal Multiple Access (NOMA) is integrated into the VLC framework. This study focuses on power allocation within the NOMA-VLC framework, with the goal of maximizing user rates while ensuring fairness. Simulation results show that EnCOA outperforms other algorithms in power allocation within the NOMA-VLC framework, especially under varying user numbers, residual interference, LED application scenarios, and shifts in photodetector alignment. EnCOA consistently demonstrates efficient power distribution and superior performance under complex communication conditions. Therefore, EnCOA is of significant importance in solving global optimization problems and power allocation challenges in NOMA-VLC systems.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131577"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.optcom.2025.131568
Liwen Wang , Sheng Liu , Geng Chen , Yongsheng Zhang , Chuanfeng Li , Guangcan Guo
The development of vector optical fields has brought forth numerous applications. Among these optical fields, a particular class of vector vortex beams has emerged, leading to the emergence of intriguing optical skyrmion fields characterized by skyrmion numbers. The optical skyrmion fields are well-defined by their effective magnetization and possess topologically protected configurations. It is anticipated that this type of optical structure can be exploited for encoding information in optical communication, even under perturbations such as turbulent air, optical fibers, and general random media. In this study, we numerically demonstrate that the skyrmion numbers of optical skyrmion fields exhibit a certain degree of robustness to atmospheric turbulence, even though their intensity, phase and polarization patterns are distorted. Intriguingly, it is also observed that a larger difference between the absolute values of two azimuthal indices of the vectorial structured light field can lead to a superior level of resilience. These properties not only enhance the versatility of skyrmion fields and their numbers, but also open up new possibilities for their use in various applications across noisy channels.
{"title":"The robustness of skyrmion numbers of structured optical fields in atmospheric turbulence","authors":"Liwen Wang , Sheng Liu , Geng Chen , Yongsheng Zhang , Chuanfeng Li , Guangcan Guo","doi":"10.1016/j.optcom.2025.131568","DOIUrl":"10.1016/j.optcom.2025.131568","url":null,"abstract":"<div><div>The development of vector optical fields has brought forth numerous applications. Among these optical fields, a particular class of vector vortex beams has emerged, leading to the emergence of intriguing optical skyrmion fields characterized by skyrmion numbers. The optical skyrmion fields are well-defined by their effective magnetization and possess topologically protected configurations. It is anticipated that this type of optical structure can be exploited for encoding information in optical communication, even under perturbations such as turbulent air, optical fibers, and general random media. In this study, we numerically demonstrate that the skyrmion numbers of optical skyrmion fields exhibit a certain degree of robustness to atmospheric turbulence, even though their intensity, phase and polarization patterns are distorted. Intriguingly, it is also observed that a larger difference between the absolute values of two azimuthal indices of the vectorial structured light field can lead to a superior level of resilience. These properties not only enhance the versatility of skyrmion fields and their numbers, but also open up new possibilities for their use in various applications across noisy channels.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131568"},"PeriodicalIF":2.2,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143222211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel high-sensitivity vector magnetic field (MF) sensor based on two parallel Fabry-Perot interferometers (FPIs) is proposed and experimentally validated. Firstly, a thin-core fiber is interposed into a quartz capillary to form a cantilever beam structure FPI1. The experiment confirmed that FPI1 achieved a high strain sensitivity of 52.21 p.m./με. Then, FPI1 is firmly attached to the magnetostrictive material Terfenol-D, converting the MF action into linear axial strain applied to FPI1, and the sensitivity of its MF intensity and direction reached 401.1 p.m./mT and −134.3 p.m./°, respectively. Finally, a reference interferometer FPI2 was matched to FPI1 to produce the harmonic vernier effect sensor S1. The MF intensity and direction sensitivity of S1 reaches −6.453 nm/mT and 2.8499 p.m./°, respectively, which enlarged the MF intensity and direction sensitivity of FPI1 by 16.2 times and 21.2 times, respectively. In short, the proposed MF sensor can measure both MF strength and direction. This sensor is easy to manufacture, low-cost, structurally robust, highly sensitive, and has a wide measurement range. It is one of the important choices for vector MF sensors in practical applications.
{"title":"Ultra sensitive vector magnetic field sensor based on Fabry-Perot cavity bonded with Terfenol-D rod","authors":"Zihao Guo, Chao Jiang, Ling Gao, Bowen Han, Han Zhang, Xiaoshan Guo, Simei Sun, Tianqi Yan, Huiling Huang","doi":"10.1016/j.optcom.2025.131572","DOIUrl":"10.1016/j.optcom.2025.131572","url":null,"abstract":"<div><div>A novel high-sensitivity vector magnetic field (MF) sensor based on two parallel Fabry-Perot interferometers (FPIs) is proposed and experimentally validated. Firstly, a thin-core fiber is interposed into a quartz capillary to form a cantilever beam structure FPI<sub>1</sub>. The experiment confirmed that FPI<sub>1</sub> achieved a high strain sensitivity of 52.21 p.m./με. Then, FPI<sub>1</sub> is firmly attached to the magnetostrictive material Terfenol-D, converting the MF action into linear axial strain applied to FPI<sub>1</sub>, and the sensitivity of its MF intensity and direction reached 401.1 p.m./mT and −134.3 p.m./°, respectively. Finally, a reference interferometer FPI<sub>2</sub> was matched to FPI<sub>1</sub> to produce the harmonic vernier effect sensor S<sub>1</sub>. The MF intensity and direction sensitivity of S<sub>1</sub> reaches −6.453 nm/mT and 2.8499 p.m./°, respectively, which enlarged the MF intensity and direction sensitivity of FPI<sub>1</sub> by 16.2 times and 21.2 times, respectively. In short, the proposed MF sensor can measure both MF strength and direction. This sensor is easy to manufacture, low-cost, structurally robust, highly sensitive, and has a wide measurement range. It is one of the important choices for vector MF sensors in practical applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131572"},"PeriodicalIF":2.2,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1016/j.optcom.2025.131581
Erick Ipus, L. Ordóñez, O. Mendoza-Yero
We propose and demonstrate, both theoretically and experimentally, a direct interferometric method for calibrating liquid crystal spatial light modulators. This method uses a single-phase mask to generate a zero-order light-free interference pattern after appropriate spatial filtering. The interference pattern is recorded and post-processed to determine the spatially dependent irradiance response of the liquid crystal display as a function of the gray levels of the associated image mask. This method allows global and local phase calibration without altering the optical setup. Our experimental results corroborate that, apart from the known dependence of the phase response on the wavelength of light, liquid crystal displays can exhibit inhomogeneous phase behavior due to imperfections or edge effects.
{"title":"Direct calibration of liquid crystal spatial light modulators using a single-phase mask","authors":"Erick Ipus, L. Ordóñez, O. Mendoza-Yero","doi":"10.1016/j.optcom.2025.131581","DOIUrl":"10.1016/j.optcom.2025.131581","url":null,"abstract":"<div><div>We propose and demonstrate, both theoretically and experimentally, a direct interferometric method for calibrating liquid crystal spatial light modulators. This method uses a single-phase mask to generate a zero-order light-free interference pattern after appropriate spatial filtering. The interference pattern is recorded and post-processed to determine the spatially dependent irradiance response of the liquid crystal display as a function of the gray levels of the associated image mask. This method allows global and local phase calibration without altering the optical setup. Our experimental results corroborate that, apart from the known dependence of the phase response on the wavelength of light, liquid crystal displays can exhibit inhomogeneous phase behavior due to imperfections or edge effects.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131581"},"PeriodicalIF":2.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.optcom.2025.131578
Johan Nilsson
We derive and assess an explicit analytic expression for the power conversion efficiency (PCE) of high-power continuous-wave optical fiber amplifiers with counter-propagating pump and signal in the presence of quenching, excited-state absorption, and background loss. The expression is uniquely simple to evaluate. A crucial assumption is that the level populations and thus the gain do not depend on the signal and pump powers separately, but rather on their ratio. In the ideal, “balanced”, case, this ratio remains constant throughout the amplifier, which is possible when the signal gain is equal to the operating pump depletion. This is achieved for certain (balanced) combinations of fiber length and input signal and pump power. With these assumptions, the PCE depends only on the spectroscopy and cross-sectional geometry of the gain fiber, but not depend on the absolute power.
We use the equations to calculate and optimize the balanced PCE of homogeneously broadened cladding-pumped Er3+-doped fiber amplifiers based on phosphorus-rich silica fibers. Cases which fulfill as well as deviate from the ideal balanced assumptions are considered. The resulting PCE agrees well with that of well-established numerical simulations in most investigated cases, but agreement gets worse at large deviations from the ideal assumptions. The calculations are sufficiently fast for optimized curves to be updated real-time when parameters (e.g., describing quenching) are changed.
We believe that our approach is valid for a range of realistic systems, including, for example, Yb-doped and Tm-doped fiber amplifiers as well as inhomogeneously broadened systems. We also discuss criteria for the expression's validity and provide tests which are straightforward to evaluate in the balanced case. Validation in more general, “unbalanced” cases, is more difficult and may in many cases require comparisons to iterative numerical simulations.
{"title":"Explicit analytic efficiency equation for saturated counter-pumped fiber amplifiers: Application to cladding-pumped erbium-doped fiber amplifiers","authors":"Johan Nilsson","doi":"10.1016/j.optcom.2025.131578","DOIUrl":"10.1016/j.optcom.2025.131578","url":null,"abstract":"<div><div>We derive and assess an explicit analytic expression for the power conversion efficiency (PCE) of high-power continuous-wave optical fiber amplifiers with counter-propagating pump and signal in the presence of quenching, excited-state absorption, and background loss. The expression is uniquely simple to evaluate. A crucial assumption is that the level populations and thus the gain do not depend on the signal and pump powers separately, but rather on their ratio. In the ideal, “balanced”, case, this ratio remains constant throughout the amplifier, which is possible when the signal gain is equal to the operating pump depletion. This is achieved for certain (balanced) combinations of fiber length and input signal and pump power. With these assumptions, the PCE depends only on the spectroscopy and cross-sectional geometry of the gain fiber, but not depend on the absolute power.</div><div>We use the equations to calculate and optimize the balanced PCE of homogeneously broadened cladding-pumped Er<sup>3+</sup>-doped fiber amplifiers based on phosphorus-rich silica fibers. Cases which fulfill as well as deviate from the ideal balanced assumptions are considered. The resulting PCE agrees well with that of well-established numerical simulations in most investigated cases, but agreement gets worse at large deviations from the ideal assumptions. The calculations are sufficiently fast for optimized curves to be updated real-time when parameters (e.g., describing quenching) are changed.</div><div>We believe that our approach is valid for a range of realistic systems, including, for example, Yb-doped and Tm-doped fiber amplifiers as well as inhomogeneously broadened systems. We also discuss criteria for the expression's validity and provide tests which are straightforward to evaluate in the balanced case. Validation in more general, “unbalanced” cases, is more difficult and may in many cases require comparisons to iterative numerical simulations.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131578"},"PeriodicalIF":2.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.optcom.2025.131567
D.L. López-Méndez , C.E. Rivera-Ortiz , Celia L. Gomez , J.P. Padilla-Martínez , L.C. Gómez-Pavón , P. Zaca-Morán
In this paper, we report an experimental study of passive Q-switching in a fiber optic laser induced by a carbon black pigment solution with reverse saturable absorption (RSA) properties. The solution was contained in a borosilicate capillary tube with an inner diameter of 125 μm and a length of 1.5 cm, which facilitated the alignment of the optical fibers and the integration of the solution for nonlinear characterization and pulse generation in a laser cavity. The solution was characterized by Fourier Transform Infrared (FTIR) spectroscopy and non-linear analysis was performed using the P-scan technique at 1550 nm by a high-gain amplifier using a pulse width of 10 ns and a frequency of 2 kHz. The results show a nonlinear absorption coefficient () of 1.49 × 10−6 m/W and a third-order nonlinear susceptibility (χ(3)) of 8.2 × 10−16 m2/V2. The pulses generated in an optical fiber laser with a ring-cavity configuration, using the carbon black pigment solution, showed an initial repetition frequency of 16 kHz at a pump power of 33 mW, which increased to 36 kHz when the power was raised to 130 mW, emitting at a wavelength of 1533 nm. To the best of our knowledge, this is the first demonstration of using carbon black pigment solutions for pulse generation in optical fiber lasers, which is an accessible, efficient, and low-cost alternative for optical communication applications.
{"title":"Passive Q-switching of a fiber optic laser induced by carbon black pigment solution","authors":"D.L. López-Méndez , C.E. Rivera-Ortiz , Celia L. Gomez , J.P. Padilla-Martínez , L.C. Gómez-Pavón , P. Zaca-Morán","doi":"10.1016/j.optcom.2025.131567","DOIUrl":"10.1016/j.optcom.2025.131567","url":null,"abstract":"<div><div>In this paper, we report an experimental study of passive Q-switching in a fiber optic laser induced by a carbon black pigment solution with reverse saturable absorption (RSA) properties. The solution was contained in a borosilicate capillary tube with an inner diameter of 125 μm and a length of 1.5 cm, which facilitated the alignment of the optical fibers and the integration of the solution for nonlinear characterization and pulse generation in a laser cavity. The solution was characterized by Fourier Transform Infrared (FTIR) spectroscopy and non-linear analysis was performed using the P-scan technique at 1550 nm by a high-gain amplifier using a pulse width of 10 ns and a frequency of 2 kHz. The results show a nonlinear absorption coefficient (<span><math><mrow><mi>β</mi></mrow></math></span>) of 1.49 × 10<sup>−6</sup> m/W and a third-order nonlinear susceptibility (χ<sup>(3)</sup>) of 8.2 × 10<sup>−16</sup> m<sup>2</sup>/V<sup>2</sup>. The pulses generated in an optical fiber laser with a ring-cavity configuration, using the carbon black pigment solution, showed an initial repetition frequency of 16 kHz at a pump power of 33 mW, which increased to 36 kHz when the power was raised to 130 mW, emitting at a wavelength of 1533 nm. To the best of our knowledge, this is the first demonstration of using carbon black pigment solutions for pulse generation in optical fiber lasers, which is an accessible, efficient, and low-cost alternative for optical communication applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131567"},"PeriodicalIF":2.2,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.optcom.2025.131534
Wenting Yu , Xingchen Li , Longfei Yin , Kaiduo Liu , Lei Chen , Tiantian Liu , Xuewen Long , Guohua Wu
LiDAR detection is very sensitive to the surface roughness of objects, which will affect the detection and identification results of the objects. The orbital angular momentum (OAM) spectrum can also be used with LiDAR to detect objects, but there are currently no research papers analyzing the impact of roughness in this scenario. In this study, a roughness model and a projection measurement method were used for numerical simulation. The analysis showed that when the wavelength is , and the correlation length is 1 mm, roughness does not affect the rotational symmetry of objects identified the OAM spectrum. When the correlation length is 5 mm and 10 mm, and the root mean square of the surface roughness is , the roughness does not affect the determination of the rotational symmetry of the target. Experimentally, this study built an optical architecture for detecting the symmetry of objects using OAM spectra. Using a 532 nm laser, the study measured five-leaf clover objects with four different roughness levels (320 mesh, 600 mesh, 2000 mesh, and 10,000 mesh). The experimental results show that using OAM spectra to detect the rotational symmetry of objects is insensitive to surface roughness, which is consistent with the simulation results. This study can promote the further application of orbital angular momentum in LiDAR target recognition.
{"title":"Effect of roughness on object identification using OAM spectrum","authors":"Wenting Yu , Xingchen Li , Longfei Yin , Kaiduo Liu , Lei Chen , Tiantian Liu , Xuewen Long , Guohua Wu","doi":"10.1016/j.optcom.2025.131534","DOIUrl":"10.1016/j.optcom.2025.131534","url":null,"abstract":"<div><div>LiDAR detection is very sensitive to the surface roughness of objects, which will affect the detection and identification results of the objects. The orbital angular momentum (OAM) spectrum can also be used with LiDAR to detect objects, but there are currently no research papers analyzing the impact of roughness in this scenario. In this study, a roughness model and a projection measurement method were used for numerical simulation. The analysis showed that when the wavelength is <span><math><mrow><mn>0</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>um</mi><mo>≤</mo><mi>λ</mi><mo>≤</mo><mn>1</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>um</mi></mrow></math></span>, and the correlation length is 1 mm, roughness does not affect the rotational symmetry of objects identified the OAM spectrum. When the correlation length is 5 mm and 10 mm, and the root mean square of the surface roughness is <span><math><mrow><mi>α</mi><mo>≤</mo><mn>0</mn><mo>.</mo><mn>7</mn><mi>λ</mi></mrow></math></span>, the roughness does not affect the determination of the rotational symmetry of the target. Experimentally, this study built an optical architecture for detecting the symmetry of objects using OAM spectra. Using a 532 nm laser, the study measured five-leaf clover objects with four different roughness levels (320 mesh, 600 mesh, 2000 mesh, and 10,000 mesh). The experimental results show that using OAM spectra to detect the rotational symmetry of objects is insensitive to surface roughness, which is consistent with the simulation results. This study can promote the further application of orbital angular momentum in LiDAR target recognition.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"579 ","pages":"Article 131534"},"PeriodicalIF":2.2,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.optcom.2025.131574
Yang He , Ziang Gao , Zhengshan Xu , Tonggang Zhao
The phenomenon of Bound States in the Continuum (BICs), recognized for its remarkable ability to suppress radiation loss and achieve ultra-high quality factors (Q-factors), has garnered significant attention in recent years, particularly in the study of metasurfaces. BICs enables resonant modes with exceptional Q-factor, presenting immense potential for applications in the design of optical devices. This study introduces an asymmetric metasurface designed to generate quasi-bound states in the continuum (Q-BICs) modes, highlighting the critical influence of structural geometry and intentional symmetry breaking in achieving Q-BICs and enhancing their Q-factors. By carefully tuning the structural parameters of metasurface units, BICs and Q-BICs modes demonstrate outstanding performance in fields such as optical sensing, nonlinear optics, and optical modulation. These modes can achieve Q-factors up to 9644 and sensitivity of 127 nm/RIU. Metasurfaces based on BICs offer innovative approaches for design of next-generation high-performance optical devices, with promising applications in biological sensing, optical filters, and energy-efficient optical communication systems.
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